This specification relates to cloud computing.
Cloud computing is network-based computing in which typically large collections of servers housed in data centers or “server farms” provide computational resources and data storage as needed to end users. Some cloud computing services provide access to software applications such as word processors and other commonly used applications to end users who interface with the applications through web browsers or other client-side software. Users' electronic data files are usually stored in the server farm rather than on the users' computing devices. Maintaining software applications and user data on a server farm simplifies management of end user computing devices. Some cloud computing services allow end users to execute software applications in virtual machines.